1. Field of the Invention
The present invention relates to an outboard motor, and more particularly to an improved engine layout within a cowling of an outboard motor.
2. Description of Related Art
Outboard motors typically include a power head supported by an upper housing. A clamping bracket usually secures the upper housing to a transom of an associated watercraft. The upper housing also supports a lower unit that includes a propeller or similar propulsion device. An engine within a cowling of the power head drives the propeller via a drive train. The drive train commonly includes a drive shaft, which extends generally vertically through the upper housing, and a propeller shaft, which lies at about a 90 degree shaft angle with the drive shaft. A gear set couples the drive shaft to the propeller shaft. The propeller shaft extends in generally a horizontal direction and support the propeller at an aft end of the propeller shaft. Power from the engine is transferred from the drive shaft to the propeller shaft through the gear set to rotate the propeller.
In connection with portable outboard motors, the weight and drag associated with a portable outboard motor desirably is minimized in order to improve the performance of the outboard motor as well as to ease handling and transporting the outboard motor. Smaller size without sacrificing performance thus is desirable. As such, prior portable outboard motors have attempted to reduce the front-to-back dimension of the outboard motor's power head.
One prior approach involves an inclined cylinder arrangement within the cowling. That is, an axis of the cylinder is inclined or skewed (within a horizontal plane) relative to a longitudinal axis of the cowling. The cylinder axis remains normal to a vertical axis about which the drive shaft rotates, but lies to one side of the cowling's longitudinal axis. Japanese Patent Laid-Open No. 60-38293 discloses an example of this approach. An induction system, which includes a carburetor, is arranged on the side of the cylinder in the space freed within the cowling by the inclined cylinder arrangement. While this engine layout reduces the longitudinal dimension of the engine in an attempt to provide a compact engine design, the layout inhibits the arrangement of other engine components on the engine in a manner further reducing the engine's physical size.